Applications such as Time Difference of Arrival (TDOA) or Time of Arrival (TOA) methods for location determination rely on tight synchronization of the clocks of a plurality of devices such as access points. For example with TDOA for every nanosecond of uncertainty between access point (AP) clocks there is a foot of uncertainty in the spatial solution. AP clocks for example are naturally unsynchronized because of slight differences in the quartz crystals used to set clock frequencies. In addition, clock variations may occur due to temperature, age and clock jitter.
One solution for providing clock synchronization is distributing a clock via wires between the APs. This solution provides very precise and reliable synchronization, but adds difficulty and expense to deployment of the network and is inflexible regarding the repositioning of the APs over time.
Another solution is synchronizing APs through a wireless method, making deployment less expensive and more flexible regarding the repositioning of the APs over time. While wireless synchronization adds flexibility and reduces cost, it suffers from the unreliability of the wireless medium. For example, in some facilities, such as large manufacturing facilities, the line of sight between wireless devices may be interrupted, for example by the movement of a large overhead crane. In addition, multipath between wireless devices may also introduce error in synchronizing clocks.